Target interceptor radar aircraft trainer



July 8, 1952 E. A. LINK 2,602,243

TARGET INTERCEFTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet l ANGLE u NIT) (GROUND SPEED UNIT) EDWIN A. LINK. INVEN on ATTORNEYS Filed March 20, 1944 July 8, 1952 E. A. LINK TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER 8 Sheets-Sheet 2 l2 r xmea (FIGHTER ALTITUDE TRANSMITTER) 535 l I I l 1'78 I 5a 578 sca-sao-a 303 I5 I I4 I I 4 2% 42 1 ass 534 I40 552 I? see 1 I38 264 29a 2 269 0 POTENTIOMETER (ATTITUDE DRIVE .UNIT 49 TAKE-OFF 9* UNIT) :24 p 300 see :93 4ae l no I 332 as 146 FIGHTER o 6 RECORDER 3001 28; 950 300b 5? FQGV 124a.

us 30| (SANBORN EQUIPMENT) 492 I24 INVENTOR.

ATTORNEYS y 8, 1952 E. A. LINK 2,602,243

TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet S {Iii EDWIN A. LINK INVENTOR- ATTORNEYS.

July 8, 1952 E. A. LINK TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER 8 Sheets-Sheet 4 Filed March 20, 1944 FIG. 4A

m L T .m m A w M E .337 8, 1952 E. A. LINK 9 TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet 5 EDWIN A. LINK.

INVENTOR. Mm

ATTORNEYS July 8, 1952 E. A. LINK TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet 6 EDWIN A.L1NK.

INVENTOR. BY A;

ATTORNEYS.

July 8, 1952 E, A. LINK 2,602,243

TARGET INTERCEPTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet 7 AT TORNEYS y 8, 1952 E. A. LINK 2,602,243

TARGET INTERCEIPTOR RADAR AIRCRAFT TRAINER Filed March 20, 1944 8 Sheets-Sheet 8 AD F Z FIG. IO EDWIN A. LlNK. INVENTOR.

ATTORNEYS.

i atented July 8, 1952 UNH'EED s'ra'ras aren't eerie 'rsnon'r rN'rEaoEr'roR' mnmnseam TRAINER This invention relates to a device for use in training personnel in the use of radar equipment, and more particularly, in the training of personnel to fly an airplane by means of radar.

In order that the general nature of this invention may be better understood; reference is made to Fig; 8 which is a schematic view of one kind of radar screen or C scope ll and range meter lfi to which the pilot of a' combat plane may refer when piloting the plane by means of radar.

Fig. 8 shows that the pilots screen and range meter are side by side. The pilots screen is connnonly referred to as the C scope'and has upon its face a plurality of horizontal a's-well as-a'plurality of vertical lines, A scale is associated with each set of lines, and it will be seen that the central vertical line is designated E, while the lines to either'side or this zero-line are successively designated by increasing increments of up to 90;

The horizontal linesare likewisedesignated in' increasing increments of l5 beginningwith the designation of minus 15 for the lowermost linearid continuing up to plus 15. V V

The range meter is provided with a needle adapted to move over two scales one above the other graduated from zero to ten. Means are provided whereby the scales are selectively used, the upper scale being used to indicate ranges of over one mile in increments of even miles, and the lower scale being used to indicateranges or less than one mile in increments of tenths of miles.

One typical use of radar is in a fighter plane which is attempting to intercept a target plane. It "is'this particular situation which the preferred embodiment of my invention will be described as simulating, although it will be readily apparent that the invention may readily be applied to the simulation of all types of navigation by radar.

In order that the objects of my invention may be more readily understood the geometrical relationships between a fighter plane and a target plane should be borne in mind. Inasmuch as it is assumed that it is the fighter which is equipped with radar, it is the position of the target rela-- tion to the fighter which is considered.

Three factors will locate the position of the target relative to the fighter:

1. Target azimuth angle, which is the angle between the fighters longitudinal axis and the projection of the line of sight from the fighter to-the target-on the'plane through the lateral andlongitudinal axes of the fighter, Azimuth is measured from the end of the projection of the 21 longitudinal axis corresponding to the nose of the plane clockwise or" counterclockwise through 180, but the specific type of radar indicating equipment being considered only indicatesazimuth up to left or right. It azimuth is greater than 90 the target is'not shownu'po'n the Scope- 7 Howevemmy ,in entien a plica e to other typas of radar receiving equipment, as will be later ana rams; k I

This definitionl is illustrate'd in Fig. Q WhQI'B the line Ldesi'gnates the direction of'flight and the fighters (F) lo'r'i'gitudinal' axis;- the line' S designates the projection o'fth'e line of sight fror'n' the fighter F'to' the target (T) on theplane through ha ais al.andlQneitlldinm a s c e fi hter; and l eene e'Adesienaiesthe azim reci l ye cn anslaywh ch is the an between the-line of sightfrom the fighter to the target andthe plane through, the lateral and longitudinal axes of the; fighter.-

This definition is illustrated in Eigl.,1Q where P illustrates the plane or the lateral and 1on gitudinal axes of the fighter (F) for the case when the fighter is in level flight, TSR is the line of sight 'fronr'the fighter to the target (T) and A is the target elevationangle I v r V By virtue of" the? foregoing definitions}- move-r merits of the-fighter about its axes'willchange the azimuth andelevation' angles. H

3'. Target-slant range, which is the distance along thefline of sight mm the fighter (F) to the target ('I InFig? l0' 'target slant rangeis illustratedbythefline 'rrsR. p o

It 'is' these threefacto'rswhich are given by the e cape" ah'djrange meter carried by a real fighter plane EQUi-PDdjWith radar. In real radar carrie'd'by "afighte'r plane the plane is' equipped with means which cause the image on the scope to bepo's'itioned according'to' the just defined azimuth and elevation angles? of the target. Also, the radareqiupmem causes thie rangemeter to register in accordance with the "distance of theftarget from the fighter; The radar indicatin'g'nieans" therefore indicate the azimuth; 'ele vation angle and range of 'the target; The radar equipment carried-by the;fightfer, inandfofitself formsno part of this invention andf'therefore is n51; hemm shown madam-.3 aewever. siif ficie'nt description of th'e parts of the ra ar equipment used with rn'y invention will be'given hereinafter to 'enable' those "skilled in thefield of radar to -'practicethis invention;

When the radar equipmentcarried by a plane is set in 'operati'on, if a target planeffbe within the field of operation" of the equipment, an image such as that shown at T in Fig. 8 appears upon the screen. This image is produced by parts of the real radar equipment which may form a part of my invention, as later more fully explained.

The azimuth of the target as previously defined is conveyed to the pilot of the radar equipped plane by the position of the image on the screen relative to the vertical line marked zero. If the image appeared as shown in Fig. l' the azimuth of the target would be 30 degrees right. The target elevation angle is indicated to the pilot by the position of the image relative to the scale at the right of the screen, and in the illustrated case is plus 50 degrees. At the same time the range meter shows the slant range of the target from the fighterin the illustrated case the slant range being four and one-half miles. If the radar equipment continues in operation, and the target remains within the scope of operation thereof, the position of the target relative to the fighter in terms of azimuth, elevation angle and range is continuously given by the scope and range meter. The position of the target relative to the axes of the fighter as shown by the scope and meter changes in response to the following movements of the target:

l-changes in the latitude of the target 2changes in the longitude of the target 3--changes in the altitude of the target Furthermore, the position of the target relative to the axes of the fighter as shown by the radar indicatingmeans changes in response to the following movements of the fighter:

4 changes in the latitude of the fighter 5-changes in the longitude of the'fighter 6-changes in the altitude of the fighter 7-changes in the position of the fighter about its vertical axes 8changes in the position of the fighter about its longitudinal axis 9-changes in the position of the fighter about its transverse axis.

As far as the first six mentioned factors are concerned it is deemed unnecessary to show in detail how changes in each of these factors affect the position of the target relative to the fighter in terms of the three basic concepts defined above. It is clear that the relative positions of two points in space in terms-of azimuth, angular difference in height and distance may change as either point changes its position in any one of the three possible directions of movement, or combinations thereof. Considering the last three mentioned factors, it is clear that a change in the position of the fighter about its vertical axis, i. e., a turning of the fighter, will produce a change in the azimuth of the target. As far as factor 8 is concerned, let us assume that the target is 90 from the nose of the fighter, i. e., directly abeam, and that the fighter changes its position about its longitudinal axis-that is, it banks. It is clear that the target elevation angle will be changed by an amount equal to the bank. And as far as the last mentioned factor is concerned, in the event the target is directly ahead of the fighter, i. e., its azimuth is zero, a change in the fighters position about its lateral axis-i. e., a diving or a climbing thereof, will produce a change in the target elevation angle by an amount equal to the change about the lateral axis.

v The preferred embodiment of this invention includes an aviation trainer which comprises a fuselage universally and rotatably mounted upon a stationary base. This trainer in the preferred embodiment of my invention represents the fighter plane. The fuselage may bank, climb, dive and turn indefinitely in either direction, these fuselage movements being accomplished by the student in the fuselage who, by means of the rudder pedals in the fuselage which actuate a turning motor, may cause the fuselage to turn in either direction.

By means of the control column or stick which is also in the fuselage the student may cause the fuselage to bank, climb and pitch by means of the banking, pitching and climbing bellows which are actuated by the movements of the control column. All of these movements of the fuselage in and of themselves form no part of the present invention, and for a complete disclosure thereof reference is made to United States Patents 1,825,462 and 2,099,857.

However, the instant invention adds to the interior of the fuselage at a place visible to the student the previously described radar indicating means, viz., the C scope and range meter. Other types of radar equipment and radar indicating means may be readily adapted for use with my invention. Hereinafter, when a radar equipped plane is referred to in the description, a plane equipped with the illustrated type of radar indicating means is intended.

Upon a table remote from the trainer fuselage is a recorder which represents the target, and this recorder may under the control of an operator be made to move in any direction and at varying rates across a chart on the table. Therefore the direction and speed of the targets movement is simulated by the direction and speed of the target recorders movements.

Also mounted upon the same chart and table is a recorder which represents the fighter. This recorder is of the type described in United States Patent 2,179,663. Its movement over the chart is automatically directionally responsive to changes in the heading of the trainer and its speed of movement varies according to the assumed speed of the trainer. The direction and speed of the fighters movements are therefore simulated by the direction and speed of this second recorders movements.

The position of the target recorder on the chart at all times represents the assumed latitude and longitude of the target, while the position of the fighter recorder on the chart at all times represents the assumed latitude and longitude of the fighter. The record made by the recorder 28 shows the assumed course over the ground of the Link trainer. This record, in conjunction with a record made by the recorder 26, may be used in post analysis of the problem flown by the student pilot in the Link trainer.

These two recorders are mechanically coupled and connected to the radar indicating means so that a movement of either one relative to the other, through an intermediate system of electrical and mechanical elements, produces the same changes in the position of the image on the radar scope and in the range meters reading that corresponding real changes in the latitude and longitude of a real target and of a real fighter would produce on the radar scope and meter in the fighter.

Amanual control'whereby the operator may set into the mechanism the assumed altitude of the target is provided, and the assumed altitudeof the fighter is automatically changed and introduced'into the apparatuses will be later pointed out. As the assumed altitude of the fighter or of the target is changed, through electrical and mechanical means the radar indicating means are changed just as are the real radar indicating means carried by a real fighter when corresponding real changes in target or fighter altitude occur.

Further, means are provided to change the radar indicating means in response to a turning, banking and pitching of the fuselage of the trainer, caused by the movements of the controls inthe trainer, in simulation of the changes which occur in the radar indicating means carried by a realfighter when the fig ter makes corresponding movements. It should be noted that thefactors of target azimuth and target elevation angle may change in response to the turning, banking, climbing anddiving-cf the plane equipped with radar, and that the radar indicating means respend to these movements. This is becavse radar equipment is'designed to indicate the position of the target relative to the longitudinal, lateral and vertical axes of the radar equipped plane. Latitude. longitude and altitude of the radar equipped plane-also are determining factors, but as far as the target is concerned, the only determining factor'sare latitude/longitude and altitude. -In

other words, the target may be considered to bea point having location only.

It is the main object of this invention to produce means whereby the radar indicating means installed in a grounded trainer may be made to respond to the above-outlined nine determining factors in simulation of the responses of radar indicating means carried by a plane in actual flight to target and to'radar equippeclplane n1ovem'ents. With my invention it is possible for the student in the trainer to control the trainer, in response to the signals indicated on the screen in' the trainer, just as a real pilot in a plane would control the plane in response to corresponding signals. Thus it is, possible for the student to control the Link trainer so that the image remains on the zero azimuth and zero ele vation angle lines in Fi 8, just as the pilot in a real plane so keepsthe image on his screen when he desires" to erc'ept an enemy craft. Other simulated situations, it will be understood bythose skilled in the 'art, may be practiced by the use of my invention. I

' It is a closely related object of thisinvention toprovide adevice for training'in navigation by radar without using real radar propagation and reception equipment.

Numerous other related objects will become'apparent as the description proceeds.

In order that the nature of my invention may be better understood reference is made to the accompanyingndrawings wherein a preferred em" bodiment is shown.

In the figures,

Fig. 1 shows 'a grounded aviation trainer of the type disclosed in United States Patents 1,825,462 and 2,099,555? together with table upon which is mounted a chart and the target and fighter recorders. Other associated parts of the invention are also shown in this figure.

Fig.2 shows in detail certain of the structural parts .of .myinvention and the general outline of thewhole invention. in diagrammatic form.

Fig-3 is a detailed view of the target andfighter recordersflthe meanscorinectingthe same, and means for. determining ground'rang'e as well as one of the components of azimuth! vention, to be a radar equipped fighter.

Fig. 6 discloses. the means used. to introduce into theapparatus the factor of altitude er. the fighter. I y g Figf'l discloses means for integratingfihe factors of ground range and altitude diifercnce to produce the factors of altitude angle and slant range, and means formodifyingthe altitudean gle to produce the elevation angle.

' Fig- 8 disclosesthe radar indicating means within the trainer fuselage. 7

Figs. 9 andlO illustrate someof the basic geometrical relationships between aradar equipped planeand atarget plane.

The fighter Referring .now to Fig. 1, it will be seen that my invention includesa trainerof the type generally referred to as a Link trainer. Thisltrainer is assumed, in the illustrated embodiment .of myritil'iis trainer comprises a stationary base It) and afuselage l2. The fuselage I2 is mounted upona uni versal joint l3 shown in Fig. 2 which in turn rests upon a maincentral spindle I l which is rotatably mounted in base Iii. Octagon I5 is attached to fuselage .12. The fuselage l2is sufficiently large to accommodatea student who may enter the fuselage by means of door lfi-and, a 'seat (not shown). is provided within the fuselage for the student. Ahood It may be used to completely encompassthe student within the trai'nerso that in the flying of the same he must rely completely upon the instruments which are in the trainer in a position corresponding to the :posi-; tionof the instruments in a real plane. The radar indicating-C scope is designated [1 and the range meter 19.

'Within the fuselage 12 are a pairof rudder pedalslea'which simulate the rudder pedals of a real plane, By a manipulation of these rudder pedals the student may energizethe turning motor 20 to cause the trainer fuselage l2 to rotate relative to base "11in either direction about its vertical axis inst as the pilot of a real plane may correspondinglycause the plane to turn. Also, within the fuselage I2 there is provided a control stick orcolumn [3b by which the student may cause the fuselagelfi to drive or climb or bank relative to base vIll in either direction in simulation of the manner that a pilot causes areal plane to performcorresponding movements. Th turning of the fuselage I2 is possible because ofth'e rotatable mounting of spindle I4 in base It], while the climbing, diving and banking are made possible by means of the mounting of the fuselage l2 upon the previously-mentioned universal joint 13.

The previously-mentioned United States Patents, 1,825,46 2 and 2,099,857 disclose in detail means for causing the fuselage l2 to turn, climb, dive and bank'in simulation of the movements of a real plane v in actual flight and, therefore,. the movements of the rudder pedals and control stick Seen upon chart 24 is the target recorder designated generally 26 and the fighter recorder des- 'ignated generally 28. These recorders are shown in detail in Fig. 3, to which reference is now made.

The target recorder comprises two substantially identical parallel members designated generally 30 and 3| connected by aycentral elevated transverse member 33; This arrangement permits the fighter recorder 28'to move under target recorder 26. Members '30 and 3| and their associated parts are substantially identical so only a detailed description of member 80 will be given. -Member '30 comprises two horizontal plates 32 and 34 held apart by spacers 36. Two vertical shafts 38 are rotatably mounted in and held by the plates 32 and 34. Mounted upon the lower end of each of the vertical shafts is a synchronous motor 42 .each of which through a reduction gear train 44 drives a propelling wheel 46 which rests upon the chart'24 shown in Fig. 1. A set of conventional slip rings and brushes 48 is associated witheach of the shafts 38 to permit indefinite rotation of shafts 38, motors 42, gear trains 44 and propelling wheels 46 and at the same time keep the motors 42 connected to their remote source of electric power.

Rigidly affixed to the top of each of vertical shafts 38 is a large spur gear 50 which meshes at all times with a middle spur gear 52. This large gear is rigidly affixed to the vertical stub shaft 54 which is held by plate 34 to correctly position gear 52 at all times. Rigidly fixed to shaft 54 is bevel gear 56 within housing 58 and meshing with gear 56 i another. bevel gear60 which is rigidly affixed to horizontal shaft 62. Rigidly aflixed upon the outside end of horizontal shaft 62 is anti-backlash worm gear 64 which is driven by worm 66 formed rigidly affixed tohorizontal shaft 68. A bearing containedin block I8 which is rigidly affixed to plate 84 isprovidedto properly position horizontal shaft 68 and a crank 12 is affixed to the end of horizontal shaft68. V The virtue of the foregoing arrangement, it will be understood that by turning crankj'l2, which it is contemplated shall be done manually by the instructor, the middle gear 52 may be rotaied and consequently gears 50, vertical shafts 38, motors 42, gear trains 44 and propelling wheels 46 will be turned about their vertical axes. The instructor may therefore position propelling wheels 46 in any direction through 360,

Horizontal shaft 62 is driven by the bevel gears 56 and 60. Upon the'other end of this shaft is another bevel gear (not shown) in housing I5 which cooperates with bevel gear I6 which, through a system (just like the previously-described system) comprising'vertical shaft 54, intermediate gear 52, driving two other gears 50 mounted upon vertical shafts 38 each carrying a motor 42', set of gear trains 44' and propelling wheels 46', may rotate the corresponding parts to position the propelling wheels in any given direction.

;llvhengver crank. 1.2, is urned, therefore, all

,ing motors 42 and 42' four of the main vertical shafts 38 and 38' are turned as arethe driving motors 42 and 42' and propelling wheels carried by each of these shafts. The driving motors and propelling wheels turnin the same direction and through the same angle so that their directions are at all times parallel. The instructor may, therefore, cause the motors 42 and 42' to drive the target recorder inany direction across the chart 24. The given direction in which the target recorder is moving at any instant may be ascertained by a reference to the azimuth scale I8 rigidly affixed upon plate 34 and the pointer rigidly affixed to the upper end of shaft 38. The instructor may, by a reference to the azimuth indicating means I8, 80 cause the target recorder to move in the direction in which it is assumed that the target plane is movi Fig. 4 shows the means used to overn the rate of travel of the target recorder, which rate may be varied according to the assumed ground speed of the target plane. The mechanism shown in Fig. 4 is referred to in the art as the ground speed unit, and is designated in Fig. 1 by 8 I.

In Fig. 4 is shown a constant speed motor numbered 82 upon the output shaft of which is rigidly fixed spur gear 84 driving a larger gear 88 which is rigidly affixed to splined shaft 88. Drum 90 is mounted upon splined shaft 88 in a manner to permit it to slide along the shaft and to rotate with shaft 88. Rigidly affixed upon this drum 80 is an upraised cam portion 92 as shown. The upraised portion 92 begins at the right end of drum 90 and progressively encircles the drum until it completely surrounds it at its left end as shown in Fig, 4. A roller cam follower 94 is carried by contact arm 96 which is connected to wire 08. Arm 96 has a contact point 91. This contact strip is carried by insulating block I00 which is suitably fixed to a supporting means (not shown). A second contact strip I02 having a contact point I03 is connected to a second wire I04 and a third contact strip I06 is connected to wire I08. Contact strip I06 is connected by means of pin I 09 to member I I I which carries screw 3'. The drum 80 and cam portion 92 which is affixed thereto are moved along splined shaft 88 by means of bracket I I8 which in turn is moved by the nut I I2 and stub shaft I I 4 whenever threaded shaft I I6 is turned by means of the flexible cable I I8, gear train I20 and crank I22.

The three wires 98, I04 and I08 are contained in the cable I24 which, as shown in Figs. 2 and 3, connects with the target recorder junction box I I5. The three wires connect to each of the drivthrough the slip rings alg hough the detailed connections are not shown in Wire 98 is connected to a source of alternating current while wire I08 is connected to a source of direct current. Wire I04 is a common return. Whenever roller cam follower 94 i upon the upraised cam 92 contact is made between points 91 and I03 and by means of elements 96, 98, I02, I03 and I04 the source of alternating current energizes the motors 42 and 42' and the target recorder moves across the chart. However, the instant roller cam follower 94 moves off cam 92 and contacts drum 90, contacts 91 and I03 break and strip I 02 contacts screw II3, so by means of elements I04, I08, I09, III and H3 the source of direct current is connected to the motors 42 and 42. This connection immediately stops these motors, thereby preventing coasting of the tar et recorders By means of crank I22 the instructor may position the drum 90 and cam 92 along splined shaft 88 to cause the synchronous motors 42 to run varying proportions of the time and, consequently, the instructor may govern the distance traveled by the target recorder in a given length of time over chart 24. The assumed rate of travel of the target plane is proportional to the distance traveled by the target recorder in a given time interval.

A graduated dial I34 is geared to the crank I22 as shown. This dial I34 is preferably calibrated in miles per hour and by referring to it and a suitable pointer (not shown) the instructor may cause the target recorder to move over the chart at the desired rate, thereby simulating the assumed rate of travel of the target plane.

By means of the previously-described mechanism the instructor may therefore causethe target recorder to move over the chart in anydesired-direction corresponding to the assumed di:

rection of flight of the target plane. Also, the instructor may vary the rate of travel of the target recorder to simulate different assumed rates of travel of the target.

The fighter recorder Also seen in Fig. 3 is the fighter recorder 23. This recorder is of the type described in United States Patent 2,179,663 and as shown in Fig. 2, this recorder includes a. teletorque receiver I46. A teletorque transmitter I33 is provided, and upon the input shaft use of this transmitter is fixedly-mounted a gear I42 which meshes with gear I44 afifixed to the main spindle I4 to rotate therewith.

Teletorque transmitter I36 is connected through cable I38 to the teletorque receiver I66 which is a part of recorder 28. Teletorque receiver I 56 also has a central shaft (not shown) referred to as its output shaft, and a gear is likewise rigidly afiixed upon this shaft. The teletorque transmitter I38 and teletorque receiver I l-6 are of the well-known type wherein a rotation of the shaft of the teletorque transmitter through a given angle produces a rotation of the central shaft of the teletorque receiver through the same angle. By selectively connecting the wires connecting the teletorques, the output shaft of the receiver may be made to turn in either direction. When the input shaft of the transmitter is turned in one direction, the output shaft of the receiver always turns in a given direction. A reversal of the direction of rotation of the input shaft of the transmitter results in a reversal of the direction of rotation of the output shaft of the receiver. Whenever the terms teletorque transmitter and teletorque receiver are hereinafter used the corresponding parts of a system of this type are designated.

As described in the United States Patent 2,179,663 whenever fighter I2 is rotated through a given angle the rotation of gear I4 5 causes a rotation of the input shaft M6 of the teletorque transmitter IE8. Consequently, rotation of the output shaft of teletorque receiver IE5 results, and by means of suitable gearing the propelling wheels I68 of the fighter recorder 23 are turned through the same angle and in the same direction as the rotation of fighter I2. Therefore, fighter recorder 28 is directionally responsive to the rotation of fuselage I2 so that the direction of its travel over chart 26 corresponds at all times to the assumed direction of flight of the fighter plane I2.

Means will now be described for governing the rate of travel of flghter'recorder 28 over the chart 2:: according to the assumed speed or the fighter I2.

Referring now to a plane in actual flight, it will be realized that the rate of travel of the plane depends upon two factors, first, the throttle setting and secondly, the attitude of the .plane, that is, whether it be climbing or diving. The farther open the throttle the faster the vplanes movement and, of course, a diving of theplane increases its speed while a climbing has the opposite. effect.

Referring now to. Figs. 2 and 2A, ittwill be'seen that inside fuselage I2 is. a throttle lever .156 pivoted at the point I52 and having connected at its lower end a link I54 which in-turn is pivotally connected to the upper end of arm I56 pivoted at I58. Link IE6 is connected to-the pitch action walking-beam IEM which is pivoted upon the stub shaft .Ifith carried by arm I660 which in turn is aflixed uponthe left end of shaft 256. Shaft 2 16 is rotatably mounted in brackets 236 whichare aifixed to the floor of fuselage I 6. Arm 246a is aflixed upon the right endof shaft 2 56 and depending link 2461) pivotallyattached to arm Zeta, has its lower end afiixed to a portion of the revolving octagon I5. The pitch action walking beam I66a has pivotally connected thereto the link I62 which in turn is. connected to leverI6 l as shown. Lever I64 is rigidly affixed to shaft I66. which is pivotally mounted in bracket, I63 which in turn is rigidly affixed to the bottom Ilfl of fuselage I2.

The just described arrangement of partsis disclosed in U. S. Patent 2,099,857, and it is sufficient to know. that upon a pushingv tothe left in Fig. 2, to which figure reference is now made of throttle lever I56, which action simulates the opening of thethrottle in a plane in actual flight, the upper end of lever I64 movesto the right. A movement of the throttle lever in the oppo site direction reverses the direction of movement of lever I64. A divingof fuselage I2 causesthe upper end of. lever I64 to move to theright in Fig. 2, while a climbing of fuselage I2 produces opposite motion of the lever. It will be seen in that figurethat to the upper end of lever I64 is connected cable I'I-Z whichis wound around a pulley-I'M which is rigidly mounted upon the springbiased input shaft of the teletorque transmitter I76. This teletorque transmitter, which is known as the fighter ground speed transmitting teletorque, is connected by means of the electrical cable I18 in Fig. 2.to the fighter ground speed receiver teletorque I86 which is a part of the ground speed unit 6| I shown in detail in Fig. 4. 1

Reference is now made to Fig. 4 which discloses the ground speed unit designated in Fig. l by 8!. In Fig. 4 it will be seen that the fighter ground speed receiver teletorque I66 has the usual output shaft I82 and a disc I86 afiixed'thereupon. Rigidly attached t o the disc is bracketIBE which carries a contact roller I 88. which bears against the unseen side of the circular contact carrying member I96. The unseen side of the member I90 carries two 180 segements which are shown in Fig. 4A and numbered Isl and I6Ia. These 180 segments are insulated from one another, but, their ends are close together as shown so that roller I88 may contact both simultaneously if the roller isappropriately positioned with respect thereto. Eachof the segments is connected electrically to one of the circular plates 11 I92. or I94 uponthe other side of disc I90. The circular plates are also insulated from one another. A brush I96 is at all times in contact with plate I92 while brush I98 likewise contacts plate I94 at all times. A conductor 200 connects brush I96 with one terminal of the reversible followup motor 202 while conductor 204 connects brush I98 with the other terminal of this motor. Whenever the roller I88 is moved by receiverteletorque I80 so that it is in contact with only one of the 180 segments motor 202 is energized and turns in agiven direction and through a'gear train and the gear 206 the motor drives disc I90in a given direction until contactroller I88 contacts both of the 180 segments, at which instant motor 202 stops. On the other hand, if contactroller I88 is moved by means of teletorque receiver I80 until it contacts only the other 180 disc motor 202 is energized and turns in the opposite direction thereby turning disc I90 in the opposite direction from the first cited case until contact roller I88 again contacts both of the 180 segments, at which instant the motor 202 stops. This arrangement is, therefore, of a conventional follow-up type.

It will therefore be realized that if the output shaft I 82 of fighter ground speed receiver teletorque I80 is turned in one direction motor 202 rotates. contact plate I90 in a given direction through the same angle as the rotation of the shaft I 82, while if the .outputshaft of the receiver teletorque is rotated in the opposite direction motor 202 is energized to rotate disc I90 in the opposite'direction and through a corresponding angle.

. This means of energizing a follow-up motor to drive a disc as a result of the rotation fthe output shaft of a receiver teletorque is used because of the limited torque of a teletorque receiver. such an arrangement is used in several places throughout my invention and whenever it is stated hereinafter that the rotation of the shaft 01' a teletorque receiver is used to energize a follow-up motor to drive another membera system substantially the same as that just described will be intended.v

Referring still to Fig. 4, it will be seen that disc I 90 is rigidly mounted upon horizontal shaft 208 upon the other end of which is rigidly afilxed spur gear 2 I which meshes with rack 2I2. This rack carries a bracket 2 I4, by means of members 2I5. Splined shaft 2"; is free to rotate within bracket 2I4. Upon the right end of this splined shaft is rigidly aflixed spur gear 2 I8 which meshes with the gear 84 which, it"will be recalled, is rotated by constant speed motor 82. Drum 220 is mounted upon splined shaft 2I6 in a manner to be rotated thereby yet allowing this drum to slide along the splined shaft. An upraised cam portion 222 encircles drum 220 in exactly the same manner that upraised cam portion 92 shown in the upper part of Fig. 4 encircles drum 90. An insulating block 224 and a plurality of contact strips designated generally by 226 are provided as is a roller cam follower 228 and a plurality'of wires 230 which connect to the contact strips as shown. Inasmuch as the construction and operation of the roller 228, strips 228 and wires 230 in response to a rotation of the drum 220 and cam 222 is an exact duplicate of the previously-described functioning of the corresponding elements shown in-the upper part of Fig. 4, it is deemed unnecessary to point out in detail the functioning of these parts. It is sufiicient to know that the wires'230 are contained in the cable I24a shown 12 in Fig. 2 which connects to the fighter recorder 28. Carried upon two of the vertical shafts of recorder 28, as is more fully described in the U. S. Patent 2,179,663, are two synchronous motors (only one shown) designated by 234. These motors are connected by means of gear trains 23 6 to the propelling wheels I48 of the fighter recorder.

Referring again to Fig. 4, it will be seen the follow-up motor 202 by means of the gear train 206, disc I90, shaft 208,- gear 2I0, rack 2I2 and bracket 2I4 positions the drum 220 and cam 222 along splined shaft 2I6 according tothe angular position of the output shaft I82 of fighter ground speed teletorque receiver I80. Therefore, the proportion of time that fighter recorder 28 is propelled by its motors 234 depends upon the angular position of the shaft I82 of fighter ground speed receiver teletorque I80.

Inasmuch as the position of arm I84 showniri nected to teletorque receiver I shown in Fig. 4,

it will be understood that a movement of throttle I 50 affects the position of contact roller I88 which governs through the intermediate described means the position of drum 220 and cam 222 along splined shaft 2I6. The rate of the travel of fighter recorder 28 is therefore dependent 'upon the position of throttle I50 and, of course, the specific connections are such that the farther throttle I50 is positioned to the left in Fig.2 the farther to the right along splined shaft 2l'6 are placed drum 220 and cam 222. Therefore, an opening of throttle I50 causes recorder 28 to move a larger proportion of the time, thereby simulating a greater assumed ground speed of the fighter I2, while a closing of the throttle has a contrary effect.

Referring now to Fig. 2A it will be seen that bracket 238 is rigidly aifixed to the bottom I10 of the trainer fuselage and shaft 240 i rigidly held by this bracket. This shaft connects to the Walking beam I80a in order that the position of arm I64 will be the differential result of the position of throttle'l50 and the attitude of fighter I2, i. e., Whether the fuselage be climbing or diving. Shaft 240 is connected to arm I64 so that when the trainer fuselage dives arm I84is moved in the same direction that it is moved when throttle 'I 50 is open and when the trainer fuselage is in a climbing position arm IE4 is moved in theopposite direction just as is the case when throttle I50 is closed. v Inasmuch as it has been shown that the posi; tion of member I04 through teletorque transmitter I16 and the mechanism shown in the lower part of Fig. 4 determines the rate of travel of fighter recorder 28 it is deemed unnecessary to show further that a diving of the trainer fuselage increases the rate of travel of recorder 28 and that a climbing of fuselage I2 results in the opposite effect. I

From the foregoing, it will be understood that the direction of movement of fighter recorder 28 over the chart 24 is automatically responsive to changes in the direction of fighter 28 so that the recorder travels at all times in accordance with the heading of fighter I2. Furthermore, the rate of movement of recorder 28 is at all times automatically responsive to the assumed rate of travel or ground speed of the fighter I2, whichrate depends upon the two factors of throttle setting and that Means for determining azimuth.

It has been previously explained that the azimuth from a radar equipped plane to the target is shown upon the radar indicating means carried by the plane by the horizontal position of the image on the C scope. Azimuth has been defined as the angle between the fighters longitudinal axis and the projection of the line of sight from the fighter to the target on the plane through the lateral and longitudinal axes of the fighter. Reference is made to Fig. 9 where the line L designates the direction of flight and the longitudinal axis of the radar equipped plane; S desighates the projection of the line of sight from the fighter to the target T on the plane through the lateral and longitudinal axes of the fighter; and the angle A designates the azimuth.

As previously explained, it will be understood that azimuth depends the relative gem graphic positions of the target and fighter, that is, if the target moves in any ction other than along the line of azimu changed. Like wise. any change in the position of the fighter above the earth except along the line of sight changes a. nuth. A second factor which affects azimuth is the dire ion of flight of the figl' ter with respect to th Jarget. if the fighter cha g its compass direction of flight, azimuth is changed.

Means will now be disclosed for automatically ascertaining the component of azimuth which is determined by the relative geographic positions of the fighter and target above the earths surface.

Reference is made again to Fig. 3 which shows the fighter recorder 28 and the target recorder 26. Inasmuch as each of these recorders covers an area upon the chart 24 representative of many square miles of the earths surface a specific point upon each of these recorders must be selected to represent the exact spot at which the fighter l2 and target are respectively located.

As shown in Fig. 3, the fighter recorder 23 is equipped with an inking wheel 2:32 rotatably mounted in the lower forked end of a Vertical shaft 244. The fighter plane is assumed to'be at the point where the bottom of inking wheel 242 rests upon the chart 25. This point is coincident with the axis of shaft 2%. Rotatably mounted upon the upper end of shaft 244 is a block 246 which slides in the track 248 of the horizontal bar 259. Rigidly afiixed to the right end of bar 259 as seen in Fig. 3 is vertical shaft 252 which extends up through and is rotatably-supported by extension 254 of the central member 33 of the target recorder. Spur gear 256 is rigidly afixed to vertical shaft 252 and meshes with gear 258 which is fixed upon the input shaft 2% of target compass bearing tele torque transmitter 252. This teletorque transmitter is connected by means of the wires carried in cable 264 with the target compass bearing receiving teletorque 266 shown in Fig. 5. Target compass bearing receiver teletorque 256, as seen in Fig. 2, forms a part of the attitude take-off unit25l' shown to be mounted sight from the fighter I2 to the target.

14 uponthe'rear of the octagon I75 of the fighter 12.

The target plane. is assumed to be located at the point where the longitudinal'axis of vertical shaft 252 intersects the chart 2G. The bearing from the position of the fighter l2 to the position of the target may be ascertained, therefore, by determining the angle between north on the chart 24 and the line of sight from the target recorder to the fighter recorder. This concept is'i'llustrated in Fig. 9 where the point represents the positon of the'fighter recorder, T represents the position of the target recorder, the vertical lines run north and south, north being at the top of the chart, and the line S represents the line of The tar,- get compass bearing is given by the angle 3.

Bearing in mind the preceding mechanical and theoretical discussion, referring to Fig. 3, if the target recorder 25 remains stationary and the fighter recorder 32} moves so that the inking wheel 2 32 travels across the chart 24 in any direction other than along the line of sight, block 2&6 will cause bar 25a to rotate about the axis of vertical shaft A rotation of gear 256 therefore results and the input shaft 2% of target compass bearing teletorque transmitter 262 is rotated. A rotation of the output shaft 263 of target compass bearing receiver teletorque 266 therefore results. Teletorque 266 is shown in Fig. 5, to which reference is now made.

Rigidly afiixed upon shaft 268 is a contact roller 2'! which, as a result of its movement,- energizes follow-up motor 212 in exactly thesame'way that follow-up motor 292 is energized, Motor 2'12 turns through an intermediate gear train (213) gear 216 which is rigidly affixed upon splined shaft 273. Upon the other end of this shaft is rigidly aflixed bevel gear 279 which drives its companion 28! which is rigidly affixed to shaft 283. This shaft, it will be seen, drives bevel gear ill which is the primary drive of differential designated generally as 2%. A'rotation of the primary drive results in a corresponding rotation of the output shaft 282 of this differential and consequently gear 28d which is rigidly affixed upon the other end of this shaft is rotated. Gear 286 meshes with gear 28 i. and is free to rotate upon shaft 238. The rotation of gear. 285 causes arctation of gear 299 which is affixed upon the input shaft 2% of the azimuth trans-. initting teletorque 28:3. This teletcrcue is connected by means of the wires contained in cable 295. with the azimuth receiving teletor ue 2% shown in Fig. 2 to be a part of the potentiometer drive unit sec.

Potentiometer drive unit 366 comprises three pctentiometers, one of which is controlled by azimuth receiving telctorque 293 through a follow-up system similar to that previously de scribed. The potentiometer unit is positioned in accordance with the position of the output shaft of the receiver teletorque see to establish an electrical value in direct linear proportion to the assumed azimuth of the target from the fighter; as determined by the output of azimuth receiving telet-orque 2M2. The potentiometer then feeds this establishedelectrical value by means of cable time into the Sanborn. equipment designated 36 in Fig. 2. This equipment is often times referred to in the art as the echo simulator, and being known to the prior art forms no part of my invention except when combined with the parts of my invention. The Qanhornequipment, in response to the electrical value fed thereinto by the azimuth potentiometer generates a signal inaccordance with the potentiometer determined electrical value and feeds this signal by connection 3001) into the intermediate frequency stage of the real radar equipment which is associated with the fighter I2 and designated in Fig. 2 by 303. The C scope and range meter are shown in Fig-'2 to be a part of the radar equipment. The illustrated radarequipment is of the type designated by United States Army number SCR520-B. This signal fed into the radar equipment by the echo simulator is the same signal that would be fed into the radar equipment carried by a plane in actual flight if the azimuth of a real target were the same as that represented by the position of azimuth receiving teletorque 298. The radar equipment therefore positions the image on the C scope horizontally, which direction gives the azimuthal position of the target, just as the image is positioned on the C scope when the azimuth of a real target is equal to that determined by the previously described apparatus of this invention. When the radar equipment is of the SCR520-B type, the Sanborn equipment or echo simulator is of the type referred to by U. S. Army designation BC934-T4. The combination of SCR520-B radar equipment and of BC934-T4 echo simulators is known to the prior art, but in the prior art devices the three potentiometers associated with the echo simulator to set up an electrical value in the simulator according to azimuth, elevation angle and range were manually set according to the three assumed factors of azimuth, elevation angle and range. My invention resides, therefore, in the disclosed means for introducing into the simulator the assumed factors of azimuth, elevation angle and range.

Also, in the known combination of SCR520-B radar equipment and BC934-T4 simulators, means are provided under the control of the radar operator for regulating certain parts of the equipment. When my invention is used with the just mentioned types of radar and echo simulators, the radar operators equipment is not changed from the prior art, and the radar operators functions are unchanged. (The radar operator should not be confused with the student pilot.) For example, the radar operator switches the apparatus to selectively use either of scales of the range meter I9, and the conventional signalling means informs the pilot in the conventional manner which scale should be read.

Because of the highly secret nature of the Sanborn echo simulator equipment and of the radar equipment, and in view of the fact that they do not form in and of themselves any part of my invention, it is deemed unwise and unnecessary to explain their detailed construction. A complete disclosure of these units may be obtained upon access to the U. S. Army equipment of the above-mentioned numbers.

Without further detailed description it will be understood that if the target recorder 26 or fighter recorder 23 changes its position relative to the other recorder in any direction except along the lines of sight, the input shaft 250 of the target compass bearing transmitting teletorque 262 likewise will be turned, and by means of the same intermediate described means the output shaft of azimuth receiving teletorque 298 will be moved. As explained, the image on the C scope will then be properly shifted to indicate the change in azimuth. Of course a movement of both the target and fighter recorders differentially affects the position of the input shaft 260 so that the image on the scope is positioned to indicate the differential change in azimuth.

It may be concluded therefore that means are provided by my invention whereby a relative. movement of the fighter recorder 28 or target re-..

corder 26 with respect to one another in any-direction other than the line of sight produces a change in the azimuth indicated by the radar.

indicating means of this invention just as a corresponding movement of a real radar equipped plane or target relative to one another produces a change in the azimuth indicated by the radar indicating means carried by the plane.

It has also been previously stated that the second factor which determines the azimuth from the radar equipped Plane to the target is the direction of flight of the plane with respect to the target. The theory of this statement may be:

realized :by a reference to Fig. 9 in which it-will be seenthat azimuth angle A will change as the radar equipped plane F changes its direction of flight. Means for simulating this feature of radar navigation are partially shown in Fig. 2

where it will be seen that spur gear 302 is rigidly affixed to the cross piece 30I which is a part of the stationary base I0. Meshing with this gear is gear 304 which is rigidly afiixed to the vertical shaft 303 having affixed upon its upper end bevel gear 306. Vertical shaft 303 is rotatablymounted within a bracket (not shown) which is affixed to crosspiece 301 of the rotatable octagon I5. Shaft 303 and gear 304 therefore rotate about gear 302 with a turning of fighter I2. This gear meshes with a driven bevel gear 303 which is rigidly affixed upon horizontal shaft 3I0 which runs fore and aft of the fighter. This shaft is held in place by bracket 3II which is affixed to to bottom I10 of the fighter fuselage I2. Shaft 3 I 0 extends through the octagon I5 of the trainer into the attitude take-off unit 251 which is mounted upon the shelf 239 affixed to octagon I5. Octagon I5 and shelf 26'9 rotate with fighter I2. Shaft 3 I 0, it will be seen in Fig. 5, has rigidly affixed upon its rear end gear 3I2 which meshes with a pair of split anti-backlash gears 3| 4 which are a-fiixed to the frame 3 I B of the differential 280. This attachment of gear 3I4 to the frame of differential 280 constitutes a secondary drive of the differential. Shaft 282 which is the output shaft of this differential is free to rotate within gear 3I4.

A rotation of fuselage I2 causes a rotation of shaft 3I0 by means of the gears 302 and 304 seen in Fig. 2 and the other gears just described. This secondary input of the azimuth differential 280 adds or subtracts from the quantity introduced into differential 280 as a result of the relative positions of the recorders 28 and 26 upon the chart 24. Shaft 282 therefore is positioned at all times according to the differential result of the target compass bearing as determined by the relative positions of the recorders modified by the heading of fighter I2. Consequently, the input shaft 292 of azimuth transmitting teletorque 294 and the output shaft of azimuth receiving teletorque 298 assumes a corresponding position. Azimuth as indicated upon the scope of the radar equipment in fighter I2 is therefore the differential result of the relative geographic positions of the fighter and target, as indicated by the positions of the recorders, and the heading of the fighter, just as azimuth indicated by radar equipment carried by a real plane in flight depends upon the two corresponding factors.

Pitching and banking of a radar equipped plane under certain conditions of flight also affect the azimuth of a target, as previously defined. My invention does not provide means for simulatingthis feature of actual radarnavigation, but inasmuch as the fighter I2 is necessarily limited in the degree of pitch or bank which may be present, and in view of the fact that it is only under certain conditions of flight that pitch and bank affect azimuth, the failure of my invention to provide means for correcting azimuth according to pitching and banking of the fighter !2 does not deprive my invention of great utility.

Means for determining target altitude angle and target slant range Target altitude angle is defined as the. angle between the horizontal plane and the. line .of

sight from the fighter to the target. This concept will be readily understood by areferenceto Fig. 10 wherein F represents the position of the fighter; P represents the horizontal. plane T.represents the target andnrepresents target altitude angle.

Target slant range has been defined. as the distance along the line of sight from thefighter to the target and will. be recognized as being represented in Fig. 10 bythe line TSR.

Target ground range is the horizontal projection of the target slant range and is represented in Fig. 10 by the line GR.

Altitude differential is the difference in'altltude between the fighter and target and is represented in Fig, 10 by the line AD.

Referring to Fig. 10 it will be realized thatthe target altitude an le A and the target slant range TSR depend only upon the magnitude of the factors of ground range GR and altitude differential AD. Means for'determining the magnitudesof these two primary quantities and for causingthe same to affect the radar indicatingmeans carried by the fighter I2 will now be disclosed. As will be disclosed a mechanical triangulating mechanism isused to. determine the factorsof target slant range and altitude angle, one sideof the triangle being representative of ground range Ground fastened to pulley 328 which is rigidly aflixed 3-23, and the other end of this string is connected to tension spring 323 which in turn is fastened to plate 2%. It will be realizedthat as the. inking wheel 2&2 ofthe fighter recorder 28 movesover the chart 24 in a direction to increase the-distance between the point upon thechart wheretheinking wheel rests and the intersection of, theiaxis of vertical shaft 252, with the chart,v block-216.. will increase its distance from the vertical shaft;2 52 and, therefore; string 318 is pulled by block246 so that pulley, 32%? rotates ina counterclockwise.

direction. The input shaft 322 of the round .range transmitten teletorque; 3;24,is therefore. ro-

tated and inasmuchas thisteletorque is connected by means of cable 328 to ,groundrangereciver .bymeans of screws 380 the gear 382.

pulley 358. tened to spring 39 lwhich in ,turnis anchored to 18 teletorque. 330 which is a part of the elevation angle unit 332, as seenin Fig. 2, the output shaft 334 of the ground range receiving teletorque 330,

as seenin Figvlgwill be rotated in the desired direction.

On the other hand, if the distance between the point where .inking wheel 242 rests upon the chart and the intersection of the longitudinal axis ofshaft 252 and the chart decreases spring 326 turns pulley 320 in a clockwise direction and the output shaft 334 of the ground range receiver teletorque 330 will rotate in the opposite direction.

.Referring to Fig. 7, fixedly mounted upon output shaft 334 is disc 336' which carries bracket 338and contact roller 343. This roller acts upon disc. 342 whichis identical with the disc I96 and disc 342 controlsthe actionof follow-up motor 3min. the same. manner that the action of follow-up motor 232 is controlled. The energiza- .tionof. fol1ow-up.motor-344 as a result of the turning .ofthe output shaft 334 of ground range receiver teletorque1330 causes a rotation of the output shaft 346 .of follow-up motor 344. Worm 3 33 is. integralwith shaft 346 and turnsthe worm gear .353 which is fixed upon shaft 352. The rotation ofthis shaft causes a rotation of the spur gear 354 which isfixed thereto and at the same time rotates control disc 342 until the roller 3 ll .rotate with and slide along splined shaft 335.

.-.A slot 3.68.15 presentin extension 334 andin this .slot. is arack 3.'ln..in.which is pivotally mounted vertical stub shaft 312. The upper end of shaft. 372 is pivotally. mounted in block 314 .which is adaptedto slide in .the groove 373 of limb. 3758, upon the other .endof which is affixed Gear 332 issuitably mounted sothat. its axis of rotation is coincident atall times with vertical line 384.

- From the preceding discussion it will be realized that .rack .353, slide 360 and. extension 364 can slide along splinedshaft 365 so that-the vertical axis designated by line 385. may. be made coincident. with .the vertical axis .384. (The vertical axis.-3;84. preferably intersects .the longitudinal axis .of splined shaft 365.)

. A string .386 .enters block. 314 at a point coincident withthevertical axis Y385 and is suitably tied in block .3.| l. This stringruns along slot 316 and at the .pointwhere it reaches the vertical axis 384; itturns upwardlytowardthe pulley 388. The string windsaround and is fastened to this pulley which is fixedly mounted upon the input shaft 390 of; slant rangetransmitting. teletorque 332, String 389 winds. aroundand has one end fastened to small pul1ey 39| :which is affixed to The othergend of this stringis fasany suitalole part.,; 3,9l .of theuhousingv of the instrument. The distance from-the point; where the .axi

3 i ers t lon itu in l. a s o pline sl ia1t;; 365, which.point;isdesignated in Big. 7

as I, to the point where a plane through -;the .v rtic aids-. 5 sha t .812. a drerpen icn to splined shaft 3fi5 intersects-the longitudinal axis of the splined shaft, which point is designated in Fig. 7 by the letter J, is assumed to be representative of the ground range as'previously defined. When the point J is coincident point I, ground range is assumed to be zero and as point J moves to the left in Fig. 7 the ground range is assumed to increase.

The distance from axis 305 along string 386 to axis 384 is representative of and proportional to target slant range. As ground range increases, target slant range also increases in this mechanical triangle.

Bearing in mind the preceding structural and theoretical discussion, it will be understood that as the inking wheel 242 of the fighter recorder 28 increases its distance from the point upon the chart where the longitudinal axis of shaft 252 intersects the chart, the pulley 320 and input shaft 322 of ground range transmitting teletorque 324, shown in Fig. 3, are rotated and consequently the output shaft 334 of ground range receiver teletorque 338 shown in Fig. 7 is rotated through the same angle and in the desired direction. As previously described the follow-up motor 344 is energized and its output shaft 346 turns in such a direction as to cause spur gear 354 to rotate counterclockwise as seen in Fig. 7. The point J therefore increases its distance from the point I and at the same time the distance between axes 384 and 385 is increased. String 386 is pulled'to the left and downward resulting in a counterclockwise rotation of the pulley 388 and input shaft 390 of slant range transmitting teletorque 392. This teletorque, by means of the wires contained in cable 393, causes the output shaft of the slant range receiving teletorque 396, shown in Fig. 2, to move through an equal angle and in the desired direction. This teletorque governs a potentiometer follow-up unit in exactly the same manner described in. the consideration of azimuth receiving teletorque 298 and its potentiometer unit in unit 300. The potentiometer unit governed by slant range receiving teletorque 336 establishes an electrical value according to the assumed slant range and this value, is fed into the Sanborn equipment which then functions in cooperation with the radar apparatus to cause the range meter l9.to indicate the assumed range represented by the position. of the output shaft of the range receiver teletorque 396. However, to accomplish this. result the radar operator must properly perform his tasks just as in the operation of the SCR520-B radar equipment in actual flight.

It is deemed unnecessary to explain in detail that as the assumed ground range decreases, ground range being represented by the distance between the point where inking wheel 242 rests on chart 24 and the point where the longitudinal axis of vertical shaft 252 intersects chart 24, the described elements operate to decrease the distancebetween axes 384 and 385 resulting in a lower reading of the range meter 19. As the slant range changes, the size and intensity of the image on the screen I! changes.

In addition to the factor of ground range which has been shown to affect target slant range, the factor of altitude diiferential also affects target slant range. This can be seen by reference to Fig. v10 where it is evident that, ground range remaining constant, an increase in altitude difference results in an increase in target slant range.

Altitude difierentialis in part introduced by the fighter altitude transmitter 459 in Fig. 1,

the detailed mechanism of which is shown in Fig. 6 which comprises a large metallic collapsible and expansible bellows 398 which is connected to the equalizer altitude tank 398a in Fig. 1 by means of connection 400. The construction and functioning of the altitude tank forms no part of my invention except as combined with the novel features being described. In the previously-mentioned U. S. Patent 2,099,857, the altitude tank is designated Ill and it is sufiicient for the purposes of this application to state that the pressure within the altitude tank is varied according to the assumed altitude of the trainer, the higher the assumed altitude the lower the pressure within the tank. The pressure within the tank is responsive to two factors, namely, throttle setting and attitude of the fuselage. When the throttle is open the pressure within the tank is made to decrease because the opening of the throttle in a plane in actual flight causes an increase in the altitude thereof. Similarly, when the fuselage is placed in a climbing position, the pressure within the tank is caused to decrease. A closing of the throttle and the assumption of a diving attitude by the fuselage results in an increase in pressure within the tank. The pressure within the altitude tank is controlled by link 400a, seen in Fig. 2A, through the conventional climb-dive valve assembly in the trainer fuselage I2.

Aflixed to the upper end of bellows 398 is member 482 which has a slot 404 and pin 406 arranged to hold one end of reciprocating arm 408 which travels in a plurality of rollers 4l0 suitably attached to plate 2. To the other end of arm 408 is afiixed string 4M which travels in pulley 4l6 suitably held by shaft 4l8 which is carried by plate M2. The other end of this string is affixed to one end of tension spring 420, the other end of which is suitably attached to anyfixed part 422 of the unit.

.A plate 424 is pivoted at the point 426 to a suitable part of the unit, and formed integrally with plate 424 is gear segment 428. A tension spring 430 is suitably attached to a corner of gear segment 424 as shown, the other end of this spring being attached to a fixed part 432 of the unit. A shaft 434 is affixed to slide 408 and has mounted thereupon toward its outer end roller: 436', and a spring 438 has one of its ends attached to the extreme outer end of shaft 434 while its other end is suitably attached to a bolt 440 carried by plate 424. A plate 442 having a slot 444 is suitably attached to the inside of plate 424 by means of a pair of bolt, nut and slot arrangements 446.

Meshing with the gear segment 428 is pinion 443 formed integrally with shaft 450 held by bracket 452. attached to plate '2. Fixedly mounted upon this shaft 450 is a large spur gear 454. The input shaft 456 of the fighter altitude transmitting teletorque 458 is connected to shaft 450 for rotation therewith and teletorque transmitter 458 is connected by means of the wires carried in cable 460 with fighter altitude receiver teletorque 462 shown in Fig. '7.

Upon the. output shaft 464 of fighter altitude receiverteletorque 462 is carried a disc 466 which hasattached thereto an arm 468 carrying a roller 410 in the same manner as the teletorque receiver I and associated parts shown in Fig. 4.

A rotation 'of the output shaft 464 of fighter altitude teletorque'receiver moves roller 410 with 21 energizing reversible follow-up motor 414, causing a rotation of its output shaft 415. A rotation of this shaft causes a rotation of worm 418 formed integrally therewith andworm gear 488 is therefore driven, causing a rotation of the splined shaft 365 upon which it is rigidly mounted. A rotation of this splined shaft will cause amovement of rack 318, the lower surface of'which comprises a plurality of teeth for coaction'with splined shaft 365. A rotation of splined shaft 385 will therefore move rack 318 in slot 368 of extension 364, and vertical stub shaft 312' and axis 385 will be moved toward or away from the point J which it will be recalled is coincident-with the longitudinal axis of shaft 365. The distance from point J to the axis 385 is representative of and proportional tothe assumed diiference in fighter and target altitudes. When axis 365' and point J are coincident the assumed altitude difierence is zero.

Referring-now to' Fig. 6, a reductiondnthe pressure within thealtitude tank in the trainer which, as previously explained results fromvan increasein the assumed altitude of the fighter 12, causes a collapsing of bellows 396 andslid-e 408 will move downwards in Fig. 6. A movement in that direction will result in asimilar movement offshaft 434 and roller 436K This roller coacting with arcuate slot 444 causes a counterclockwise pivoting ofplate- 424 resulting'in a clockwise turning of pinion 44S, gear 454 andof the input shaft'456 of fighter altitude transmitting tele-- torque 458. The output shaft 4E4 of fighter altitude receiving teletorque 462 shoWndn Fig. 7

will. therefore movev in thendesiredldirection,

resulting in an energization of follow-up motor 414 which will turn in a directionto cause splined shaft365 to move clockwise as seenfrom its left end-in'l ig'. 7. Back 318 will therefore move to'the right along slot 368 carrying with it stub shaft 312, axis 385, block'314 and the unpivot'ed end of arm 3-!8. Gear" 382 will therefore rotate about vertical shaft"'384 rotating the gear 482 which meshes therewith. This gear is rigidly afilxed upon the input shaft 484 of elevation angle transmitting teletorque'486 which is connected by means of'the wires in cable 488 with the elevation angle' receiving teletorque 498 associated with the potentiometer unit 388, seen in Fig. 2. Elevation angle receiving .teletorque 480 functions with respect to itspotentiometer unit as previously described in connection with the azimuth receiving teletorque 298, also shown in Fig. 2 except, or course, the potentiometer in unit 300 controlled by elevation angle receiver teletorque 490 is connected to the Sanborn radar equipment to cause the position. of the image upon the radar indicating means inthe trainer to vary vertically. A- vertical change, as previously described; represents a change in the elevation angle from the fighter to the target. ngain it is "deemed unnecessary to explain in detail that an increase in'the pressure within closedi11"F'ig; 7. Shown therein is a :crank492 teletorque bears to' its housing.

the splined shaft 365.v will be moved in slot 388 carryingwith'it vertical which. is connected through a gear train idesignatedigenerally 4-94 to a flexible cable- 496.

Upon the other end of this flexible cable is fixed pinion 498 which, by means of a pair of gears designated 500, drives gear 502 which is affixed to the housing of fighter altitude receiver teletorque 462. 1A rotation of the housing of this teletorque results in a rotation of the output shaft 464 of the receiver because in systems of this kind the output shaft 'of the receiver teletorque at all times bears the same relation to its housing asthe input shaft of the transmitting A rotation .of theihousing of the receiver theref-oremust result in a rotation of the output shaft of the receiver because the housing and input shaft of the transmitter are held stationary. The rotation of the output shaft 464 and roller 4'l8acting with disc 472 will energize follow-up motor 4'14 to rotate Consequently, rack- 3'18 shaft 312 and axis: 385.

Dial 504 is geared to crank 492 hy-means of gearsdesignated generally 586 and by reference to this dial and a fixed pointer (not shown the instructor may ascertain the assumed altitude of the target which-h-e has introduced into. the

mechanism.

As has been. described, the distance between the point I of Fig. '7 and the point J is at; all

times proportional to the ground range. Point the fighter altitude moves axis 385 toward point J. It sho'uldbe noticed that axis" 385 may be moved to .either side, of point J, sotthemechanism may indicatea positive'or negative .target elevation angle. Inasmuch-as the distance I-J represents ground rangd-andthe distance J- axis 385 represents altitude difference, it'isclear that the distance from axis-385 to axis' 384 represents target slant range. Also, the angle formed by the arm 318 and the splined shaft 365 must be equal to the altitude angle.

Such being the case, it is clear that as ground range is increased the distance from axis'385 to axis 384 likewise increases, so 'slant' range increases. Also, as the altitude difference increases the difference from the axis 335 to the axis 384 increases, and. slant range increases accordingly. .(If the altitude difference is zero, the target slant range is equalfto the ground range.) 8

' Asthe distance from the axis 385 to axis384 increases, the input shaft 390 of the slantrange transmitting teletorque 392 is turned and by means of cable 393 the output shaft of slant range receiving teletorque 386 shownin-Fig. 2 is rotated to. produce through the Sanborn and radar equipment an increased indication upon the range meter l9. An opposite indication results when the input. factors are such. as to cause a decreased target slant-range.

longitudinal axis ot splined i shaft- 355- and the arm 318 (or line from axis 385 to axis 384) is equal to the altitude angle. As this angle increases or decreases as a result of changes in the magnitudes of ground range or altitude difference, gear 382 is rotated proportionatelycausing a rotation of gear 482 and the input shaft 484 of elevation angle transmitting teletorque 486. This teletorque is connected'by cable 488 to elevation angle receiving teletorque 490 (seen in Fig. 2) which actuates a potentiometer drive like that previously described. The potentiometer drive, through the same intermediate means, changes the vertical position of the image on the C scope, to indicate that the target elevation angle has changed. This primary drive of elevation angle teletorque 488 therefore results in the vertical positioning of the image on the C scope in accordance with the altitude angle as determined by the mechanical triangle of F1g. 7. Means for combining this altitude angle with the pitching and banking of the trainer fuselage to produce elevation angle will be later described.

Referring now to Fig. 6, it has been mentioned that plate 424 carries a plate 442 in which is formed an arcuate slot 444 and that as slide 408 reciprocates roller 436 moving in slot 444 rotates plate 424 which causes a rotation of the input shaft 456 of the fighter altitude transmitter teletorque 458. This slot 444 and non-circular gear segment 428 are provided to change the nonlinear response of the bellows 388 to a change in the assumed altitude of the trainer to a linear rotation of the input shaft 456 of the fighter altitude transmitting teletorque 458. When the fighter I2 is at a low assumed altitude a change of, for example, 1000 ft. in its assumed altitude, results in a greater change in the pressure within the altitude tank (not shown) in the trainer fuselage, and consequently in a greater expansion or collapsing of bellows 398 than occurs when the trainer is assumed to be flying at a higher altitude and a change of 1000 feet in altitude occurs. In the use of real radar equipment in a plane, a change of 1000 feet in the altitude of the plane carrying the radar equipment, other factors being constant, will produce a given change in the elevation angle as seen on the screen. It is immaterial whether the plane is flyingat 10,000 feet or 30,000 feet when the change occurs. In order that the mechamsm of my invention function properly it is clear that for a change of a given amount in the altitude of the trainer, the input shaft 456 of the fighter altitude teletorque transmitter must rotate through the same angle regardless of whether the fighter is assumed to be flying at a high or low altitude, so that the image on the screen will properly move to reflect the change in elevation angle. Therefore, the slot 444 and noncircular gear segment 428 are used.

Also shown in Fig. 6 is a telegon transmitter 508 having a central shaft L0 which is coupled by a pair of magnets 5l2 to a shaft 5l4 which has a pinion 516 that meshes with gear 454. This telegon transmitter is known as the altitude telegon transmitter and is connected by means of the wires contained in cable 5M to a telegon receiver which drives the altimeter (not shown) in the fighter I2 as well as the altimeter 5l8 positioned near the table 22 as seen inliig. 1. The telegon system of instrument actuation is well known in the field of aviation training. Inasmuch as the functioning of the telegon instruments is substantially the samein all respects as the functioning of a teletorque system, ex

plained hereinbefore, a detailed explanation 0 this system is not deemed necessary,

Vertical speed indicator 5|9 shown in Fig. 1 functions substantially as described .in United States Patent 2,099,857.

Means for correcting altitude angle according; to pitching and banking to produce elevation angle Target altitude angle has been defined as the angle between the horizontal plane through the fighter and the line of sight from the fighter to the target.

Target elevation angle has been defined as the angle between the plane through the lateral and longitudinal axes of the fighter and the line of sight from the fighter to the target.

A comparison of these two definitions shows that when the plane through the longitudinal and lateral axes of the fighter is horizontal, target altitude angle equals target elevation angle. However, when the plane through the lateral and longitudinal axes of the fighter departs from the horizontal, target elevation angle may not equal target altitude angle. The magnitude of the difference between target elevation angle and target altitude angle caused by a departure from the horizontal of the plane through the lateral and longitudinal axes of the fighter depends upon the azimuth of the target, the altitude angle and also upon whether the departure of the lateral and longitudinal axes of the fighter from the horizontal plane is caused by a banking or a pitching of the fighter.

Specifically, let us assume that the altitude of the fighter and target are the same and that the fighter is flying directly along the line of sight from the fighter to the target. The altitude angle is equal to zero. If the fighter assumes a diving position, it is clear that the target elevation angle has become a positive quantity because there then is a positive angle between the plane through the lateral and longitudinal axes of the fighter and the line of sight from the fighter to the target. On the other hand, if under the same assumed conditions the fighter assumes a climbing attitude, a negative target elevation angle is ,produced. It is clear that under these assumed conditions the magnitude of the target elevation angle is equal to the number of degrees of movement of the fighter about its transverse axis.

If the assumed conditions are changed only in that the altitude of the target is assumed to be different from that of the fighter, the same results occur when the fighter dives or climbs.

However, regardless of whether the altitude of the target and fighter are equal if the fighter is flying directly along the line of sight to the target, a banking of the fighter through a given angles does not cause target elevation angle to differ from target altitude angle. However, if the altitude of the target is equal or not equal to the altitude of the fighter, and the fighter is flying along a vertical plane through the target and fighter, but not flying along the line of sight, a banking of the fighter does cause the elevation angle to differ from the altitude angle, but for a given number of degrees of bank the change is not as great as when the fighter is pitched about its transverse axis through the same number of degrees.

All of the precedin conditions are also true when the fighter is flying directly away from the target, that is, the azimuth of the target is However, assuming that the elevation of the target and of the fighter to be equal and the 

